It's all about using your resources efficiently and not waste time and money on creating assets that you really don't need.

i still don't understand how they did that.

it must involve some animal sacrifices and human souls.

little to no cutscenes + not much voice acting + compressed sound = low file size. This isn't rocket science people. Unless it's somehow rocket science, in which case, Nintendo devs are beasts.

Super Mario Bros. for the NES is only 31.29 KB.
Yet that game provided endless fun & is STILL fun today 28 years later.

It's not in the amount of file size.
It's in the amount of FUN size that counts.

That 1.7 GB is plenty enough.
Nintendo is the master of making things efficient & non-wasteful.
Super Mario 3D World will be amazing fun! I can just taste it!
John Lucas

Man, as well as it'll sell at 1.7 gigs, imagine how well it would have sold if they'd spent obscene amounts of time and money cramming 48.3 gigs worth of better textures and unnecessary voice acting and pre-rendered cutscenes into there just because they can. Clearly Nintendo doesn't understand modern game development.

They didn't. Galaxy 2 had in in early screens, but it was later removed. I presume because it was too taxing for the Wii.

Too bad, 'cos it looked marvelous, and I agree I'd have loved to see it in 3D World.

Heh, didn't realize that. Very impressive (despite the plethora of bugs). More than 360 hours put into that game... very impressive indeed.

But the OP forgot to mention that the other 23.3 gigs of space for SM3DL is packed with pure digital fun to accompany the game. ^_^

That's about 43 times the size of Super Mario 64 I think, lol.

The first one is 3.5GB, but the second one is 1.3GB.

Anyway, looking at these gifs it is easy to understand how it is so small, they are reusing a lot of assets. Look at that wall texture for example, repeating over and over.